A San Leandro podiatrist was charged on Friday with felony counts related to unlawfully dispensing addictive narcotics to patients, according to the district attorney’s office.

Alameda County District Attorney Nancy E. O’Malley said Dr. Tan Nguyen, 62, wrote more than 5,000 prescriptions for painkillers and other drugs in the span of one year.

During the investigation, O’Malley said undercover law enforcement agents posed as patients and visited Nguyen to request prescriptions for medication. The defendant wrote prescriptions without ever examining patients or asking any health related questions, investigators said.

Prosecutors said between June 2013 and June 2014, Nguyen wrote thousands of prescriptions for hydrocodone, known as Vicodin; oxycodone, a highly addictive narcotic painkiller; carisoprodol, a muscle relaxer; and diazepam, an anti-anxiety medication, known as Valium.

In addition to the Alameda County District Attorney’s Office, the Department of Health and Human Services, the FBI, and the Alameda County Sheriff’s Office took part in the investigation.

“Medical professionals who unlawfully supply prescriptions to controlled substances will be identified and prosecuted,” said O’Malley in a statement.

“Prescription drug use is a public safety and public health issue. These drugs are highly susceptible to misuse and abuse, which can lead to addiction, accidental poisoning or other grave consequences,” O’Malley added.

Nguyen was previously convicted in 2008 of selling illegal narcotics prescriptions, according to the district attorney’s office.